So in my car, i have diamond m5 audio speakers, powered by a 4 channel soundgate amp.
I got the amp tested, its fine, the headunit is fine, i had the whole system completely reinstalled and grounds all relocated, and they still whine super loud with the rpms.

I tried it with a different amp and headunit and it still did it.
The guy at the shop said the only thing he can think of left to try is the alternator or battery.
What do you guys think it could be?

 

Sounds like a bad ground. Run a separate ground from the alternator and see if that helps.

 

yupp its definatly caused by some interference within the body. I would closely examine your wires to see if any of the shielding might have come off. Or check ur remote cable from your amp.

 

Remote cable is good, it must be something to do with the alternator!
Ill check tomorrow

 

Ok, i recently installed a bigger alternator, i went from a 90 amp to a 120amp and it still does it, then i swapped the battery to see if that would change anything and it still does it.
So you guys recommend running another ground for the alternator?

All the stereo grounds are all grounded at the same point, and the power wires aren't crossing or paralleling with the speaker wires. they run to separate side of the car.

 

if i were u i would relocate my ground. U only get that whine when u are getting some sort of interference from the body. versus spending money trying to fix something u arent sure is going to fix mighteswell try a free solution first.

 

Do any of you guys know the locations of the grounds for the battery and alternator?

 

Multiple ground locations. Just follow the wires with your hand and a flash light. Should be pretty easy to follow a 0 gauge wire. Or is it 4 guage for the batt? I think one of them in on awheel well iirc.

 

where/how do you have your power cable and rcas ran to the amp? if you ran them close to each other (like both under the same door sill) it can cause interference just like your describing...

 

My rcas are run on the drivers side, and my power wires are all ran to passenger side.
It buzzes when i run the stereo without the car running, and when i start the car, it buzzes and whines with the rpms.
I have ground loop isolaters on the rca cables also and it is still loud.


I don't believe it has much to do with anything on the stereo at this point, The guy i had work on it said that this was the first time he has never been able to fix alternator whine.